1. Field of the Invention
The present invention relates to an antimicrobially active peptide and to its preparation and to a method for protecting and/or treating human skin against microorganisms.
2. Description of the Related Art
The epithelial tissue of mammals represents an important barrier to the surroundings and provides a first line of defense against invading microorganisms. In particular, antimicrobial peptides, of which there are many in the epidermis, participate in the defense system. They control microbial growth in the first hours after epithelial injury and during wound healing. In particular, they can be found in some inflammatory disorders of the skin.
To date, two classes of antimicrobial peptides have been discovered in mammalian skin, the cathelicidins and the β-defensins. They are induced in human creatinocytes after induction by inflammatory stimuli and act primarily as a response to injuries and not within the framework of a constant modulation of the epithelial defense mechanism.
Whereas, for example, cathelicidin PR-39 is a component of wound fluid and appears to be involved in wound healing, cathelicidin LL-37 is expressed in human skin creatinocytes at inflammatory sites in various diseases.
Defensins are small cationic peptides having a molecular weight of from 3 to 5 kDa, and they have an antibacterial and antimycotic effect. The α-defensins HD1-4 are expressed for example in human neutrophils which accumulate in infected tissue regions. The α-defensins HD-5 and HD-6 are, by contrast, produced by epithelial granulocytes.
In general, antimicrobial peptides are endogenous, gene-encoded peptides with particular importance for the early phase of defense against microbial pathogens. They can be detected within minutes to hours after the first contact with the pathogen.
However, known antimicrobial peptides do not act against all microbial pathogens in the same way; for example defensins have only an inadequate effect on infections with S. aureus, an important cause of skin infections, especially associated with atopic dermatitis.
Antibiotics are also employed preventively or curatively for controlling pathogenic microorganisms, these being substances of microbiological origin which inhibit the growth of or even kill other microorganisms. In contrast to the above-mentioned cathelicidins and defensins, antibiotics usually have selective activity. Many microorganisms have a natural insensitivity to an antibiotic, but they may also develop this so-called antibiotic resistance during growth in the presence of antibiotics.
Mutation and selection processes, and the development of resistances are causing problems increasingly frequently, not only in clinical routine but also in the manufacture of medicaments and cosmetics, with microbial pathogens which can be controlled inefficiently or not at all.
Against this background, there is a continuing need for novel antimicrobially active agents which can be employed preventively or curatively.
Against this background, an object underlying the present invention is to provide a further antimicrobially active peptide and indicate a way for producing it.